This invention relates to portable door securing devices that can be temporarily installed to the inside of an inwardly swinging entrance door for preventing unauthorized entry into a room or building. More particularly, this invention relates to improved portable door locks of the type wherein the lock is installed to extend between a door and the associated frame with a first portion of the lock being engaged with the opening within a conventional frame-mounted strike plate and a second portion of the lock being moved into abutment with and secured against the surface of the door.
The need for and desirability of portable door locks that can be used by the occupants of a building or room for securing the entrance thereof against unauthorized entry has long been recognized. Such locks are, for example, especially advantageous as a supplemental lock for temporary quarters such as a hotel or motel room since the occupants of such premises have no control over access to the keys for operating the conventionally provided locking devices. Further, although various permanently mounted auxiliary locks are sometimes provided, such devices do not necessarily provide the desired degree of protection and are not always maintained in proper operating condition.
A variety of supplemental locking devices that are easily stored and/or carried in a suitcase, purse or other container have been proposed in the prior art. With respect to the present invention, such prior art devices include auxiliary locking arrangements in which a hook-like extension in the end portion of a relatively thin locking bar is inserted in the strike plate opening of the door frame with the locking bar extending between the door and door frame and a blocking member is moved along the locking bar and secured in abutment with the inner surface of the door. Examples of devices which fall into this general classification, and because of similarity in function and use provide background for the present invention, are disclosed in U.S. Pat. Nos. 633,078; 3,416,333; 3,423,968; 3,429,151; 3,451,235; 3,475,929; and 3,596,961.
Although the locking devices disclosed in the above-referenced patents operate satisfactorily in some respects and under some conditions, presently available devices present several disadvantages and drawbacks. In this regard, the shortcomings of such prior art devices primarily result because of compromises that have heretofore been necessary in attempting to satisfy several somewhat conflicting design considerations. More specifically, a portable locking device of the type addressed by the present invention should be relatively simple and economical yet provide a high degree of security and reliability. Further, such a device should not only be configured for ease of installation and operation but should be arranged for rapid removal to permit authorized entry and allow an occupant of a locked room to quickly disengage the device and evacuate the room or building in case of fire or other emergency. Additionally, a locking device of this type must not mar or otherwise damage a door and should be configured and arranged for use with entrance doors having variously configured trim or decorative molding.
The auxiliary locks disclosed in the previously referenced U.S. patents do not appear to simultaneously satisfy or fully meet the above-mentioned design goals. For example, with the exception of U.S. Pat. No. 3,596,961, each of these references disclose locking devices in which the component that abuts the inner surface of the door extends directly outward across the adjacent door frame without accommodation for molding or trim that often surrounds the periphery of conventional entrance doors. Further, of the above-cited patents, only U.S. Pat. No. 3,596,961 and U.S. Pat. No. 633,078 disclose locking arrangements that do not require an additional device such as a padlock or integrally contained key-operated lock for maintaining the disclosed device in the fully-engaged and locked condition. Although devices employing key-operated and auxiliary locks have application to additional situations wherein a room, showcase, cabinet or other enclosure is to be locked from the outside, this feature is a distinct disadvantage when the device is used to temporarily secure the door of an occupied room or building. In particular, it is not only possible to at least temporarily misplace the necessary key, but the additional operation required to disengage the device makes it cumbersome to admit welcome or authorized persons and can make it difficult to quickly open the door should an emergency evacuation be necessary.
In addition, the prior art has not generally obtained the desired degree of security in that such devices are not arranged to withstand forces that can be exerted by a determined intruder. For example, in many of the prior art devices the component that is intended to abut the inner surface of the door must be secured in one of several predetermined positions. Oftentimes the available positions do not secure the door tightly against the frame and, when force is exerted on the outside of the door, bending moments or other concentrated forces are coupled to the locking device thereby causing the device to fail. In this regard, although previously referenced U.S. Pat. No. 3,429,151 discloses an arrangement in which the member that abuts the inner surface of the door can be tightened beyond a position in which such member is simply in contacting juxtaposition therewith, only very limited tightening or clamping action can be attained. More specifically, in the device disclosed by U.S. Pat. No. 3,429,151, the component that engages the strike plate is a flat elongated locking bar having teeth or serrations in the oppositely disposed longitudinal edges which are engaged by threads within a nut-like locking member. To provide ease of operation, the nut-like locking member includes two oppositely disposed radially extending slots that extend through the root region of the threads and permit the locking member to be slid axially along the locking bar. With this arrangement the nut-like member is rotated 90.degree. L after being urged into abutment with the door and limited tightening or clamping action is affected. The amount of tightening that is provided does not, however, exert substantial compressive force on the door and this device is further subject to the various previously-described disadvantages.
Accordingly, it is an object of this invention to provide a portable auxiliary door lock which can be used by the occupant of a room or building to securely fasten an inwardly swinging frame-mounted entrance door in a closed position; such door lock being of the type in which the a first portion of the lock engages with a strike plate or other stationary portion of the door frame and a second portion of the lock is positionable against the interior surface of the door.
It is an associated object of this invention to provide a supplemental door lock of the above-mentioned type wherein the lock is configured and arranged to permit the exertion of compressive force between the door and the adjoining region of the frame to thereby tightly clamp the door in a locked position and attain a high degree of security.
It is another object of this invention to provide a portable auxiliary door lock which is relatively simple in structure and economical to manufacture.
It is yet another object of this invention to provide a supplemental door lock that is easily operated and configured for rapid installation and removal.
Still further it is an object of this invention to provide a portable door lock that is usable with conventional inwardly swinging doors which include a variety of frame-mounted trim or decorative moldings.